For developing projects, we highly recommend you use a Teensy board to get your code working.

But
using this chip and a blank MK20DX128VLH5 or MK20DX256VLH7, you can
build your own Do-It-Yourself board that's compatible with Teensyduino
and Teensy Loader. Either chip will work. The MINI54 will automatically
detech which chip you've used and implement either Teensy 3.0 or Teensy
3.1.

These chips can also be very useful for modest volume
production of a fully custom product developed using Teensy 3.0 or
Teensy 3.1.

Teensy 3.1 has the same size, shape & pinout; is compatible with
code written for Teensy 3.0, and is well supported on the Arduino IDE
using Teensyduino. Teensy 3.1 adds several new features, due to an
upgraded microcontroller. Here are the highlights. A table of technical
specifications is show below.

Teensy 3.1 has the same size, shape & pinout; is compatible with
code written for Teensy 3.0, and is well supported on the Arduino IDE
using Teensyduino. Teensy 3.1 adds several new features, due to an
upgraded microcontroller. Here are the highlights. A table of technical
specifications is show below.